A lot of this comes down to theming. But even when you have scenes set up, scenes are made better by actors. Some scenes fit certain themes.

Aliens -
Put in a crop circle? Cattle mutilation? Government investigators? Eventually aliens for the payoff?

Country Circus-
You could put up some circus tents, carnival games, wagons, acts, etc. Actors supporting these scenes could be carnival workers, or how about zombified carnival workers?

Random Stuff - There is a lot of random stuff that just goes well in corn mazes
-Scarecrows
-Crows or Ravens (cawing sound effects coming from somewhere is also a winner)
-Graveyards (was the patch grown over a graveyard, how about instead of just putting a graveyard out there, have the "remains" of one that's now just part of the patch.

Scenes won't likely mean scares without actors (at least most of the time) but they at least can be something interesting to look at between scares.

There are three rules to designing a haunt. Unfortunately, nobody knows what they are.